Phrazebit, "What I think is going to hold Archie back is his ability to learn. Calipari found him to be uncoacheble; so far here he made very little development as a player in two years."
In fact he did improve his three point shooting from year 1 to year 2 - he doubled his success rate from .139 to .293. Its still not in the right ballpark but if can just increase it 33% this year, he'll be okay in that regard.
I think you're basically right but its also true that almost anyone can be taught if the right approach for them is used. Presumably, Archie has been taught the same way the other players have been and it may be that he requires more intensive coaching than they do. Of course that may not work either, but it's certainly worth a try.
There are people you can pay to help players with their shot mechanics, people who specialize in that and have a history of success. I can't look at his shot and even say that its wrong is some way - it looks pretty good to me, to tell the truth. But there might be a half dozen minor mistakes and his shot won't improve until all of them are corrected. He could, for example, work on them one a time and reject them all since little happened. I would guess that such shooting coaches are used to working with players who don't learn quickly with normal coaching.
Hornacek is no slouch as a shooting coach according a number of players, which means that he may not be the best person to decide that another approach could work better for Archie.
IMO, Jeff missed a great opportunity with Archie last year by not keeping him the whole season with the Bakersfield Jam. With goals regarding turn overs, assists and mid-range shots. If it meant assigning an assistant to work with him there, that would not be an inordinate expense. The main thing, though, was for Archie to get invested in helping the team win - why bother to make a good pass if all that matters is your own scoring. He's probably learned over the years that the best way to help his team win is to score as much as possible but he's at level now where that is rarely true for the best scorers in the world.